This paper looks at the case of moral philosophy in order to assess the extent to which and ways in which teacher education should respond to the liberal principle of justification. This principle states that moral and political decisions made by citizens with special kinds of influence and other coercive powers should be accountable to other citizens on the basis of good reasons. To what extent should teachers, who are empowered by the state with such special kinds of influence, be held accountable to this principle and what kind of education is needed in order to prepare teachers for such accountability? Moral philosophy stands as an informative test case because it expressly deals in the justification of judgements and actions and so it stands to reason that arguments for moral philosophy in teacher education are likely to appeal to educational values that dovetail with demands of this principle. I first identify some preliminary criteria under which activities are understood to be educationally worthwhile in the context of the broader principle of justification. I then argue that the justificatory obligations incurred by liberal citizens who adopt the role of teacher not only allow for, but also require, moral philosophy as an activity in programmes of teacher education.